WARNING: refcount bug in io_send_zc_cleanup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4fafd96910ad Add linux-next specific files for 20230203
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12876ea5480000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d2fba7d42502ca4
dashboard link: https://syzkaller.appspot.com/bug?extid=d3d1d921091f5f3a2b37
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [asml.s...@gmail.com ax...@kernel.dk io-u...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/348cc2da441a/disk-4fafd969.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e2dedc500f12/vmlinux-4fafd969.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fae710d9ebd8/bzImage-4fafd969.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3d1d9...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 18029 at lib/refcount.c:28 refcount_warn_saturate+0x107/0x1f0 lib/refcount.c:28
Modules linked in:
CPU: 0 PID: 18029 Comm: syz-executor.3 Not tainted 6.2.0-rc6-next-20230203-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
RIP: 0010:refcount_warn_saturate+0x107/0x1f0 lib/refcount.c:28
Code: 1d c0 98 46 0a 31 ff 89 de e8 f5 47 6b fd 84 db 75 a3 e8 dc 4b 6b fd 48 c7 c7 80 c0 a6 8a c6 05 a0 98 46 0a 01 e8 b9 e1 32 fd <0f> 0b eb 87 e8 c0 4b 6b fd 0f b6 1d 89 98 46 0a 31 ff 89 de e8 c0
RSP: 0018:ffffc90014c6fb68 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9000cf47000
RDX: 0000000000040000 RSI: ffffffff814c0217 RDI: 0000000000000001
RBP: ffff8880312903d0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8880312903c0
R13: ffff888031290530 R14: ffff8880312903d0 R15: ffff888031290500
FS: 00007fd438e7a700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c012ced000 CR3: 0000000078e22000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_sub_and_test include/linux/refcount.h:283 [inline]
__refcount_dec_and_test include/linux/refcount.h:315 [inline]
refcount_dec_and_test include/linux/refcount.h:333 [inline]
io_notif_flush io_uring/notif.h:35 [inline]
io_send_zc_cleanup+0x19d/0x1e0 io_uring/net.c:945
io_clean_op+0xf8/0xb20 io_uring/io_uring.c:1857
io_free_batch_list+0x48b/0x810 io_uring/io_uring.c:1477
__io_submit_flush_completions+0x4ca/0x950 io_uring/io_uring.c:1527
io_submit_flush_completions io_uring/io_uring.c:173 [inline]
io_submit_state_end io_uring/io_uring.c:2354 [inline]
io_submit_sqes+0xa61/0x1f20 io_uring/io_uring.c:2465
__do_sys_io_uring_enter+0x975/0x2810 io_uring/io_uring.c:3458
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd43808c0c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd438e7a168 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 00007fd4381abf80 RCX: 00007fd43808c0c9
RDX: 0000000000000000 RSI: 0000000000002ee6 RDI: 0000000000000003
RBP: 00007fd4380e7ae9 R08: 0000000020000000 R09: 0000000000005a01
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffa56fd88f R14: 00007fd438e7a300 R15: 0000000000022000
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.